Natsushio-class submarine

The Natsushio-class submarines were a pair of submarines constructed and operated by the Japan Maritime Self-Defense Force during the Cold War. They were a development of the Hayashio-class submarines and are sometimes considered the same class. They were small and limited in capability but were thought to be a successful class. They entered service in 1963–1964 and were deleted in 1978.

Design and description
The Natsushios were a development of the preceding Hayashio-class submarine and are sometimes considered the same class. They shared many of the same characteristics with small design improvements. They were small submarines with limited capability but considered handy and a successful class. They were air-conditioned and had good habitability for the crews. The submarines measured 61 m long overall with a beam of 6.5 m and a draft of 4.1 m. The submarines had a standard displacement of 780 LT, with a surfaced displacement of 690 LT and 850 LT submerged.

The vessels were powered by a diesel-electric system. Two shafts were powered by two Sulzer-Mitsubishi diesel engines creating 1350 bhp and two electric motors creating 1700 shp. This gave the submarines a maximum speed of 12 kn surfaced and 15 kn submerged. The Natsushios were armed with three 533 mm torpedo tubes in the bow. They had a crew of 43.